Characteristic features of fiber lasers include high output beam quality, compact size, ease-of-use, and low running cost. Fiber lasers can generate either continuous-wave (CW) radiation or pulse radiation. Pulsed operation can be achieved via Q-switching techniques. Q-switched fiber lasers are preferred for applications such as micro-machining, marking, and scientific research due to their high peak power and excellent beam quality. Q-switching is achieved by inserting an optical modulator in the laser resonance cavity to control optical loss in the cavity. In particular, the modulator functions as an optical loss switch. Initially, cavity loss is kept on a high level (low Q factor state). Laser oscillation cannot occur at this initial period, but energy from a pump source accumulates in the gain medium. Subsequently, cavity loss is switched to a low loss level (high Q factor state), so that laser oscillation builds up quickly in the cavity and generates a high peak power laser pulse. When the laser cavity is switched between low Q and high Q by the optical modulator, sequenced laser pulses are produced.